Electron discharge apparatus



Feb. 19, 1946. A. M. SKELLETT 2,395,299

ELECTRON DISCHARGE APPARATUS Filed June 29, 1944 A T TORNEV Patented Feb. 19, 1946 ELECTRON DISCHARGE APPARATUS Albert M. Skellett, Madison, N. J., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application June 29, 1944, serial No. 542,665

(ci. 25o- 157) 7 Claims,

This invention relates to electron discharge apparatus and more particularly to such apparatus including an electron discharge device of the muitlanode beam type.

One object of this invention is to enable selective magnetic deflection of an electron beam in a multianode electron discharge device. in accordance with signal pulses such that the beam will be held focussed upon any desired anode after the cessation of the signal pulse resulting in direction of the beam to such anode.

In one illustrative embodiment of this invention, electron discharge apparatus especially suitable for step-by-step switching operation comprises a cathode, a plurality of anodes mounted side by side opposite the cathode, means for producing a constant magnetic iield in the anodecathode region for normally directing the electron beam in a prescribed direction, for example, for normally focussing it upon one of the anodes, and means for producing magnetic eld pulses at an angle, for example substantially a right angle, to the constant ileld, to deflect the beam in one direction or the other, dependent upon the polarity of the pulses, so that it impinges upon any desired one of the anodes.

In accordance with one feature of this invention, means are provided for producing an auxiliary magnetic iield in the anode-cathode region, at an angle, for example substantially a right angle, to the constant eld and of an intensity dependent upon the amplitude of the beam deflection due to the eld pulses such that the beam is held focussed upon the anode to which it is deected. In one illustrative embodiment, the auxiliary held-producing means comprises a coil having its longitudinal axis normal to the direction of the constant eld and connected in circuit with the cathode and the several anodes in such manner that the amplitude of the magnetic field due thereto when the beam is impinging upon any anode is such as to maintain the beam directed upon that anode.

The invention and the above-noted and other features thereof will -be understood more clearly and fully from the following detailed description with reference to the accompanying drawing in which the single gure is in part a circuit diagram and in part a sectional view of an electron discharge device, showing an electronic switching system illustrative of one embodiment of this invention.

Referring now to the drawing, the electron discharge device therein illustrated comprises an evacuated enclosing vessel I in which there are mounted a cathode Il, a control or accelerating electrode or grid I2 encompassing the cathode, a plurality of trough-shaped anodes, I3a to |31', mounted side by side along an arc concentric with the cathode, and an arcuate screen electrode I4 having therein a plurality of apertures I5 each opposite a respective anode. The several electrodes advantageously are parallel and elongated in the direction normal to the plane of the drawing, so that when the electrodes are energized as described hereinafter an electron beam, indicated in one position at I6. of rectangular section and high current is produced.

A magnet having pole-pieces I1 is mounted outside the vessel I0 to produce a field of prescribed intensity substantially parallel to a line from the cathode II to the anode I3e. A pair of eld coils I8a and I8b are mounted in alignment on opposite sides of the vessel I0, for example on a magnetic yoke 30, and as pointed out hereinafter, produce in the region between the cathode and the anodes a magnetic iield substantially normal to the i'leld due to the magnet and of an intensity dependent upon the position of the beam. An auxiliary or pulsing coil I9 coaxial with the coils I8 is provided on the yoke 30 to produce field pulses also normal to the field due to the magnet.

Each of the anodes I3 is connected to a respective tap on one of the coils I8 and thence to the positive terminal of one of the sources 3i, such as batteries, the negative terminal of each source being connected to the cathode by way of ground as shown. Loads 22, such as relays, may be connected in circuit with the anodes. The screen electrode I4 is connected to an intermediate positive terminal of one of the sources. The electrode or grid I2 may be held at a fixed potential, positive or negative, with respect to the cathode II or may have a. variable potential applied thereto by way of a suitable input element 20. The auxiliary coil I9 is adapted to be energized from a suitable pulsing circuit 2|.

The constant field due to the magnet is made such that in the absence of fields due to the coils I8 and I9, the electrons emanating from the cathode II are concentrated into a beam focussed upon the anode I3e. If the coil I9 is energized, the electrons emanating from the cathode are subjected to two magnetic fields at right angles to each other and, consequently, the beam will be deflected so that it is substantially parallel to the resultant of the two magnetic elds. The direction and amplitude of the beam deection will be dependent, of course, upon the polarity and magnitude of the field due to the coil I9. Assume that the coil I9 is energized by a pulse such that the electron beam ls shifted from the anode lieto the anode IU. Then, as is apparent, a circuit will be completed from the anode I3! tothe cathode Il through the source 3th and a part of the coil |8b so that a magnetic eld, due to the coil l8b. normal to the constant field, is introduced into the anodecathode region. If the eld due to the coil I8b is of the proper intensity, it will be seen that the beam will be held upon the anode I3f. If, now, a second energizing pulse of proper amplitude and polarityis supplied to the coil i9, the beam will be deected to terminate upon the anode |39 so that a circuit, including a greater number of turns of the coil |8b, is completed between the anode I3g and the cathode and a field of intensity proportional to the number of turns included in the circuit is produced in the anodecathode region, the eld being normal to the constant field. As is apparent, if the field due to the coil Ib is of the proper intensityA the beam will be held upon the anode i3g.

Thus, it will be appreciated that the beam may be shifted successively from one anode to the next by pulses supplied to the coil I9 and held upon any anode to which it is deflected by virtue of the :Held due to the coil I8, this eld being of an intensity at any time determined by the position of the beam at that time, i. e.. by which of the anodes the beam is impinging upon. Stated in another way, when the beam is impinging upon any anode, it automatically adjusts the eld normal to the constant ileld to the value requisite to hold the beam upon that anode.

In the illustrative cases considered above, the polarity of the field due to the coil i9 has been assumed such as to produce clockwise deilection of the electron beam. 0i' course, if the polarity is reversed, the beam will be deiiected in the opposite, i. e., counter-clockwise, direction. Hence, the beam may be shifted from one anode to another anode upon either side of it by applywith claim 1 wherein said deflecting means comprises magnetic means for producingmagnetic gels pulses at an angle to said iii-st magnetic 3. Electron discharge apparatus in accordance with claim l wherein said means for producing said second magnetic field comprises a magnetic ileld coil connected in circuit with said source and all of said electron receiving electrodes.

4. Electron discharge apparatus comprising means including a cathode for producing an electron beam, a plurality of anodes mounted side by side opposite said cathode, means for establishing a constant magnetic field having its lines passing from said cathode to one of said anodes and of such intensity as to focus said beam upon said one anode, means for deflecting said beam to shift its terminus from said one anode to another of said anodes. and means for holding said beam upon the anode to which it is shifted. said holding means comprising means for producing a magnetic ileld substanitally normal to said constant iield and of intensity proportional to the amplitude of deiiection of said beam when its terminus is shifted from said one anode to another anode.

5. Electron discharge apparatus comprising means including a cathode for producing an electron beam, a plurality of anodes mounted opposite said cathode, means for deecting said beam to deect it selectively against any one of said anodes, and means separate from said deecting means for holding said beam upon the anode against which it is directed, said holding means comprising means for producing a magnetic field in the direction of deflection of said beam and of an intensity dependent upon which anode said beam is directed against.

6. Electron discharge apparatus comprising a cathode, a plurality of anodes mounted side by side opposite said cathode, means for producing a magnetic field having its lines extending ing an energizing pulse of appropriate polarity and amplitude to the coil I9.

In the specic embodiment of the invention illustrated and above described, the several magnetic field-producing elements are oriented so that the electron beam initially is directed upon the center anode and is deflected to one side or the other of this anode. It will be apparent that thefield-producing elements may be oriented so that initially the beam is impinging upon any other anode, for example, either end anode |3a or |31'. It will be understood also that various modications may be made in the embodiment illustrated and described without departing from the scope and spirit of the invention as deiined in the appended claims.

What is claimed is:

1. Electron discharge apparatus comprising a source of electrons, a plurality of electron receiving electrodes mounted side by side opposite said source, means for producing a magnetic field to concentrate electrons emanating from said source into a beam, means for deflecting said beam selectively to direct it against any one of said electron receiving electrodes, and means for holding said beam upon the electrode against which it is directed by said deflecting means, said holding means comprising means for producing a second magnetic ield at an angle to said rst magnetic eld and of an intensity proportional to the amplitude of deection of said beam.

2. neutron disarge apparatus in accordance from said cathode to one of said anodes to concentrate electrons emanating' from said cathode into a beam focussed upon said one anode, means for deilecting` said beam to shift its terminus from said one anode to another anode, said deflecting means comprising means for producing magnetic field pulses normal to said first neld and of an intensity to deect said beam from one anode to the next adjacent anode. andV means for producing a second magnetic eld parallel to said pulses and of an intensity at any time substantially proportional to the amplitude of deilection of said beam from said one anode, said last-mentioned means comprising a magnetic eld coil connected to said cathode and all of said anodes.

7. Electron discharge apparatus comprising a cathode, a pair of anodes, means for producing a magnetic iield having its lines extending from said cathode to one of said anodes to concentrate electrons emanating from said cathode into a beam focussed on said one anode, means for deilecting said beam to cause it to impinge upon the other of said anodes, and magnetic eld coil means connected between said cathode and said other anode and energized in accordance with current ow therebetween for producing a second magnetic eld substantially normal to said iirst eld and of intensity to hold said beam upon said other anode upon cessation of operation of said deiiecting means.

ALBERT M. SKELLETI'. 

